There are many kinds of telescopic masts of which some can be extended automatically. In connection with telescoping masts, e.g. for military use, there are special requirements to stability and accuracy. U.S. Pat. No. 4,151,534 describes a free-standing mast for an antenna including a number of telescoping tubes. U.S. Pat. No. 4,137,535 describes a telescopic mast which is controlled pneumatically. The mast includes a number of telescoping tubes that may be collapsed in a base section. A piston is integrated in each section. WO 0189981 describes a telescoping member with a nut which is rotatably fastened to a frame, a rotary pipe with thread engaging the nut. None of these inventions are adequately fulfilling the requirements to stability and accuracy.
Telescopic masts can be very high and may be used for sensors and weapons as well as for pointing out targets. High telescopic masts contain many telescoping sections. As play occurs between all adjacent telescoping sections of the mast, the play will accumulate in connection with high masts. Therefore, not the least in connection with high telescopic masts, it will very appropriate to minimise the play occurring between adjacent telescoping sections.